I am recording on a MSI Wind PC running -recent, using the integrated azalia
azalia0 at pci0 dev 27 function 0 "Intel 82801GB HD Audio" rev 0x01: apic 1 int 16 (irq 10) azalia0: codecs: Realtek ALC888 audio0 at azalia0 Everything I record has a small negative DC offset: http://stare.cz/~hans/.tmp/mike.wav I have tried using both the front and the rear mic-in plug, carefully muting the one I was not using. No difference. I have tried using three different mikes. No difference. I have tried using _no_ mike, and recording the "silence" (with the mic input _not_ muted) - the result is a wave with an almost constant negative DC ofset, sounding like white noise: http://stare.cz/~hans/.tmp/nomike.wav I have tried recording silence when the mic input is muted. In this case, silence is recorded, with no DC offset. This leads me to think that the problem is not with the mikes, let alone aucat (which I use to record the sound), but is in the hardware. Is this right? Is this a problem with voltages? A problem with my audio chip? Thank you for your time Jan OpenBSD 4.7-beta (GENERIC.MP) #0: Sat Feb 6 22:39:46 CET 2010 [email protected]:/usr/src/sys/arch/i386/compile/GENERIC.MP cpu0: Intel(R) Atom(TM) CPU 230 @ 1.60GHz ("GenuineIntel" 686-class) 1.60 GHz cpu0: FPU,V86,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,TM,SBF,SSE3,MWAIT,DS-CPL,TM2,CX16,xTPR real mem = 1064660992 (1015MB) avail mem = 1022898176 (975MB) mainbus0 at root bios0 at mainbus0: AT/286+ BIOS, date 11/19/08, BIOS32 rev. 0 @ 0xf0010, SMBIOS rev. 2.5 @ 0xfbeb0 (31 entries) bios0: vendor MICRO-STAR INTERNATIONAL CO., LTD version "1.70" date 11/19/2008 bios0: MICRO-STAR INTERNATIONAL CO., LTD MS-7418 acpi0 at bios0: rev 2 acpi0: tables DSDT FACP APIC MCFG SLIC OEMB HPET acpi0: wakeup devices P0P2(S4) P0P1(S4) EUSB(S4) MC97(S4) P0P4(S4) P0P5(S4) P0P6(S4) P0P7(S4) P0P8(S4) P0P9(S4) USB0(S1) USB1(S1) USB2(S1) USB3(S1) SLPB(S4) acpitimer0 at acpi0: 3579545 Hz, 24 bits acpimadt0 at acpi0 addr 0xfee00000: PC-AT compat cpu0 at mainbus0: apid 0 (boot processor) cpu0: apic clock running at 132MHz ioapic0 at mainbus0: apid 1 pa 0xfec00000, version 20, 24 pins acpihpet0 at acpi0: 14318179 Hz acpiprt0 at acpi0: bus 0 (PCI0) acpiprt1 at acpi0: bus 1 (P0P4) acpiprt2 at acpi0: bus 2 (P0P5) acpiprt3 at acpi0: bus 3 (P0P6) acpiprt4 at acpi0: bus 4 (P0P7) acpiprt5 at acpi0: bus -1 (P0P8) acpiprt6 at acpi0: bus -1 (P0P9) acpicpu0 at acpi0 acpibtn0 at acpi0: SLPB acpibtn1 at acpi0: PWRB bios0: ROM list: 0xc0000/0xae00! 0xcb000/0x1000 pci0 at mainbus0 bus 0: configuration mode 1 (bios) pchb0 at pci0 dev 0 function 0 "Intel 82945G Host" rev 0x02 vga1 at pci0 dev 2 function 0 "Intel 82945G Video" rev 0x02 wsdisplay0 at vga1 mux 1: console (80x25, vt100 emulation) wsdisplay0: screen 1-5 added (80x25, vt100 emulation) intagp0 at vga1 agp0 at intagp0: aperture at 0xe0000000, size 0x10000000 inteldrm0 at vga1: apic 1 int 16 (irq 10) drm0 at inteldrm0 azalia0 at pci0 dev 27 function 0 "Intel 82801GB HD Audio" rev 0x01: apic 1 int 16 (irq 10) azalia0: codecs: Realtek ALC888 audio0 at azalia0 ppb0 at pci0 dev 28 function 0 "Intel 82801GB PCIE" rev 0x01: apic 1 int 16 (irq 10) pci1 at ppb0 bus 1 re0 at pci1 dev 0 function 0 "Realtek 8168" rev 0x02: RTL8168C/8111C (0x3c00), apic 1 int 16 (irq 10), address 00:24:21:5a:a8:95 rgephy0 at re0 phy 7: RTL8169S/8110S PHY, rev. 2 ppb1 at pci0 dev 28 function 1 "Intel 82801GB PCIE" rev 0x01: apic 1 int 17 (irq 11) pci2 at ppb1 bus 2 ppb2 at pci0 dev 28 function 2 "Intel 82801GB PCIE" rev 0x01: apic 1 int 18 (irq 12) pci3 at ppb2 bus 3 ppb3 at pci0 dev 28 function 3 "Intel 82801GB PCIE" rev 0x01: apic 1 int 19 (irq 5) pci4 at ppb3 bus 4 uhci0 at pci0 dev 29 function 0 "Intel 82801GB USB" rev 0x01: apic 1 int 23 (irq 3) uhci1 at pci0 dev 29 function 1 "Intel 82801GB USB" rev 0x01: apic 1 int 19 (irq 5) uhci2 at pci0 dev 29 function 2 "Intel 82801GB USB" rev 0x01: apic 1 int 18 (irq 12) uhci3 at pci0 dev 29 function 3 "Intel 82801GB USB" rev 0x01: apic 1 int 16 (irq 10) ehci0 at pci0 dev 29 function 7 "Intel 82801GB USB" rev 0x01: apic 1 int 23 (irq 3) usb0 at ehci0: USB revision 2.0 uhub0 at usb0 "Intel EHCI root hub" rev 2.00/1.00 addr 1 ppb4 at pci0 dev 30 function 0 "Intel 82801BA Hub-to-PCI" rev 0xe1 pci5 at ppb4 bus 5 ichpcib0 at pci0 dev 31 function 0 "Intel 82801GB LPC" rev 0x01: PM disabled pciide0 at pci0 dev 31 function 1 "Intel 82801GB IDE" rev 0x01: DMA, channel 0 configured to compatibility, channel 1 configured to compatibility wd0 at pciide0 channel 0 drive 0: <ELITE PRO CF CARD 8GB> wd0: 1-sector PIO, LBA, 7647MB, 15662304 sectors wd0(pciide0:0:0): using PIO mode 4, Ultra-DMA mode 2 pciide0: channel 1 disabled (no drives) pciide1 at pci0 dev 31 function 2 "Intel 82801GB SATA" rev 0x01: DMA, channel 0 configured to native-PCI, channel 1 configured to native-PCI pciide1: using apic 1 int 19 (irq 5) for native-PCI interrupt wd1 at pciide1 channel 0 drive 0: <SAMSUNG HD502HI> wd1: 16-sector PIO, LBA48, 476940MB, 976773168 sectors wd1(pciide1:0:0): using PIO mode 4, Ultra-DMA mode 6 ichiic0 at pci0 dev 31 function 3 "Intel 82801GB SMBus" rev 0x01: apic 1 int 19 (irq 5) iic0 at ichiic0 adt0 at iic0 addr 0x2e: adt7467 rev 0x71 spdmem0 at iic0 addr 0x50: 1GB DDR2 SDRAM non-parity PC2-4200CL3 SO-DIMM usb1 at uhci0: USB revision 1.0 uhub1 at usb1 "Intel UHCI root hub" rev 1.00/1.00 addr 1 usb2 at uhci1: USB revision 1.0 uhub2 at usb2 "Intel UHCI root hub" rev 1.00/1.00 addr 1 usb3 at uhci2: USB revision 1.0 uhub3 at usb3 "Intel UHCI root hub" rev 1.00/1.00 addr 1 usb4 at uhci3: USB revision 1.0 uhub4 at usb4 "Intel UHCI root hub" rev 1.00/1.00 addr 1 isa0 at ichpcib0 isadma0 at isa0 pckbc0 at isa0 port 0x60/5 pckbd0 at pckbc0 (kbd slot) pckbc0: using irq 1 for kbd slot wskbd0 at pckbd0: console keyboard, using wsdisplay0 pms0 at pckbc0 (aux slot) pckbc0: using irq 12 for aux slot wsmouse0 at pms0 mux 0 pcppi0 at isa0 port 0x61 midi0 at pcppi0: <PC speaker> spkr0 at pcppi0 npx0 at isa0 port 0xf0/16: reported by CPUID; using exception 16 mtrr: Pentium Pro MTRR support uhidev0 at uhub2 port 2 configuration 1 interface 0 "Genius Optical Mouse" rev 1.10/1.00 addr 2 uhidev0: iclass 3/1 ums0 at uhidev0: 3 buttons, Z dir wsmouse1 at ums0 mux 0 uhidev1 at uhub1 port 2 configuration 1 interface 0 "Chicony USB Keyboard" rev 1.10/1.02 addr 2 uhidev1: iclass 3/1 ukbd0 at uhidev1: 8 modifier keys, 6 key codes wskbd1 at ukbd0 mux 1 wskbd1: connecting to wsdisplay0 uhidev2 at uhub1 port 2 configuration 1 interface 1 "Chicony USB Keyboard" rev 1.10/1.02 addr 2 uhidev2: iclass 3/0, 3 report ids uhid0 at uhidev2 reportid 1: input=1, output=0, feature=0 uhid1 at uhidev2 reportid 2: input=1, output=0, feature=2 uhid2 at uhidev2 reportid 3: input=3, output=0, feature=0 vscsi0 at root scsibus0 at vscsi0: 256 targets softraid0 at root root on wd0a swap on wd0b dump on wd0b record.adc-0:1_mute=off record.adc-0:1=224,224 record.adc-2:3_mute=on record.adc-2:3=0,0 inputs.mix_source=mic,mic2,hp,line-grn inputs.mix_mic=0,0 inputs.mix_mic2=0,0 inputs.mix_line-in=0,0 inputs.mix_hp=0,0 inputs.mix_beep=0,0 inputs.mix_line-grn=0,0 inputs.mix_line-blk=0,0 inputs.mix_line-org=0,0 inputs.mix_line-gry=0,0 outputs.mix2=216,216 inputs.mix2_source=dac-0:1,mix outputs.mix3=0,0 inputs.mix3_source=dac-4:5,mix outputs.mix4=0,0 inputs.mix4_source=dac-2:3,mix outputs.mix5=0,0 inputs.mix5_source=dac-6:7,mix outputs.line-grn_source=mix2 outputs.line-grn_mute=off inputs.line-grn=0,0 outputs.line-grn_dir=output outputs.line-grn_boost=off outputs.line-blk_source=mix3 outputs.line-blk_mute=on inputs.line-blk=0,0 outputs.line-blk_dir=output outputs.line-blk_boost=off outputs.line-org_source=mix4 outputs.line-org_mute=on inputs.line-org=0,0 outputs.line-org_dir=output outputs.line-gry_source=mix5 outputs.line-gry_mute=on inputs.line-gry=0,0 outputs.line-gry_dir=output outputs.mic_source=mix2 outputs.mic_mute=off inputs.mic=85,85 outputs.mic_dir=input-vr100 outputs.mic_boost=off outputs.mic2_source=mix2 outputs.mic2_mute=off inputs.mic2=0,0 outputs.mic2_dir=input-vr100 outputs.mic2_boost=off outputs.line-in_source=mix2 outputs.line-in_mute=on inputs.line-in=0,0 outputs.line-in_dir=input outputs.line-in_boost=off outputs.hp_source=mix8 outputs.hp_mute=off inputs.hp=0,0 outputs.hp_dir=output outputs.hp_boost=on record.adc-2:3_source=mic,mic2 record.adc-0:1_source=mic outputs.mix8=216,216 inputs.mix8_source=dac-8:9,mix outputs.line-grn_sense=plugged outputs.line-blk_sense=unplugged outputs.line-org_sense=unplugged outputs.line-gry_sense=unplugged outputs.mic_sense=plugged outputs.mic2_sense=unplugged outputs.line-in_sense=unplugged outputs.hp_sense=unplugged outputs.master=220,220 outputs.master.mute=off outputs.master.slaves=mix2,line-grn,hp,mix8 record.volume=120,120 record.volume.mute=off record.volume.slaves=adc-0:1,adc-2:3
